<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link href="https://cdn.bootcdn.net/ajax/libs/minireset.css/0.0.2/minireset.min.css" rel="stylesheet" />
  </head>
  <body>
    <style>
      main {
        width: 100vw;
        height: 50vh;
        background-color: cornflowerblue;
        display: flex;
        flex-direction: column;
        justify-content: space-between;
      }
      div {
        background-color: crimson;
      }
      div:nth-child(1) {
        height: 60px;
      }
      div:nth-child(2) {
        background-color: darkcyan;
      }
    </style>
    <main>
      <div>a</div>
      <div>aa</div>
    </main>
  </body>
</html>
